Photoelectric recording device



1952 H. w. HOFFMAN ET AL 2,583,737

PHOTOEILECTRIC RECORDING DEVICE Original Filed Sept. 6, 1945 4 Sheets-Sheet 2 TEANJVEZSE s'sc T/ON THRU PHOTO C51. 1. FKAME ,qrmvvsmr/o/v PHOTOCELLS PHOTOCELL 5 lW/ENTOES Harry Wuhan Hoffman vovev H. Hal-er 1952 H. w. HOFFMAN EIAL PHOTOELECTRIC RECORDING DEVICE 4 Sheets-Sheet 3 Original Filed Sept. 6, 1945 Patented Jan. 29, 1952 2,583,737 PHOTOELECTBIC RECORDING DEVICE Harry William Holman, Anoka,

Minn.,and

Grover H. Helmer, deceased, late of St. Louis Park, Minn., by Esther Helen Helmer, special administratrlx, St. Louis Park, Minn., asaignors to Federal Cartridge Corporation, Minneapolis, Minn., a corporation of Minnesota Original application September 6, 1943, Serial No. 501,424. Divided and this application April 28, 1947, Serial No. 744,524

8 Claims.

This invention relates to an apparatus for accurately and automatically indicating and recording movements of illuminated or lightreflective bodies past a station or plurality of stations in succession, and particularly to sensitive photo-electric apparatus for indicating and recording the operation of illuminated projectiles.

The invention has particular applicability where it is desired to indicate and record the performance of illuminated or illuminatible and reflective bodies in their movement past one or more stations. It is, therefore, an object of the invention to provide such an apparatus for indicating and recording the movement of projectiles, and particularly by photo-electric means. Itis also an object of the invention to provide a photo-electric viewing and amplifying apparatus together with indicating or recording apparatus of extreme sensitivity capable of being operated by exceedingly small changes in light density during instantaneous periods, and particularly to provide such an apparatus capable of use where the available power supply is relatively poorly regulated and is subject to frequent instantaneous variations in voltage.

Other and further objects of the invention are those inherent and implied by the apparatus herein illustrated, described and claimed.

Throughout the drawings, corresponding numerals denote corresponding parts. The apparatus is illustrated with respect to the drawings in which Figure 1 is a schematic plan or elevatlonal view of the entire system;

Figure 2 is a sectional view through one of the photo-electric stations shown at Figure l and taken in the direction of arrows 2-2 of Figure 1;

Figure 3 is a longitudinal, sectional view through either of the photo-electric cell stations of the system and taken in the direction of arrows 33 of Figure 2;

Figure 4 is a front, elevational view of one of the photo-electric devices of Figure 2 taken in the direction of arrows |4 of Figure 2;

Figure 5 is an electrical wiring diagram of an amplifier circuit such as is used in each photoelectric station;

Figure 6 is a wiring diagram together with a schematic representation of the recorder apparatus of the system; and

Figure '7 is an elevational view, partly in section, of a portion of the recording apparatus.

This application is a division of application Serial No. 501,424 filed September 6, 1943, now Patent 2,442,690, issued June 1, 1948.

Referring to Figure 1, there is illustrated a range generally designated it, along which an object such as a projectile is adapted to pass as, for example, along the path of line "-12. At one or more places along the range there are established stations for indicating and providing responsive electrical signals as a result of the passage of a projectile or other obiect past the station. Thus, along the range it there are illustrated station i and station 2, although it will be understood that in other installations it may be desirable to use more than two stations, depending upon the work to be done.-

Statlons I and 2 and any additional stations which may be utilized in the system are preferably of identical construction and each includes a photo-electric cell frame generally designated 15, having the general configuration illustrated in Figures 2, 3 and 4, although, obviously, this mechanical framework may be widely varied in accordance with the particular installation. For purposes of illustration herein it is assumed that it is desired to record the passage past Stations I and 2 cl an illuminated or illuminatible projectile, and that the projectile is moving at gunfire velocity. In such a system the photo-electric cells are conveniently housed in a framework generally designated l5, having top members it, bottom members l1 and side members It and II defining the cross-sectional space of the range through any portion of which the projectile may pass. Adiacentto the side member is there are positioned a plurality of photo-electric cellenclosing boxes generally designated 2i, 22, 23, 24, 25 and 26 of generally similar, but not identical construction. Thus, in the specific embodiment illustrated, there are six boxes, 2i and 20 being identical, 22 and 25 being identical and 23 and 24 being identical. However, the boxes 2|, 22 and 23 are arranged in transposed position with respect to boxes .24, 25 and 28. More speciflcally, it will be noted that box 2i has top and bottom walls It and II which extend forwardly to the vertical wall is. The vertical wall I! is composed of one or more vertically spaced panels, having a space thercbetween so as to form a vertical viewing aperture, as illustrated at the bracket I2 in Figure 3.

Within the box 2i there are a plurality oi baiiles 33, I4, 35 and 36, each of which has an opening cut centrally therein. The openings oi the several baiiles are chamfered at the edgetoward the right in Figure 2 (i. e. toward the thciredgesdeilncaconeofviewboundeduntbc case of box 2|) by the lines 40-4I, 42-48 (in the sectional view shown in Figure 2), and the lines 44-45 and 48-41 (in the sectional view shown in Figure 3). At the position indicated by numeral 48 within box 2|, there is positioned a photo-electric cell mounted in any suitable manner not illustrated. Hence, any light falling within the angle of view defined by lines 40-4I and 42-43 (in the sectional view shown in Fi ure 2) and any light falling within the angle of view defined by the lines 44-45 and 45-41 (in the sectional view shown in Figure 3) is free to fall uniformly on any portion of the photo-electric cell cathode. height of the photo-electric cell 48 cathode, there is a marginal area around the cone of view in which any light will illuminate part but not all of the photo-electric cell. This marginal area lies between the lines 40- and 50-5I at the upper portion of Figure 2, and between the lines 42-43 and 52-53 at the lower portion of Figure 2. Similarly, there is a marginal area between the lines 45-41 and 56-51 at the right, as shown in Figure 3, and between the lines 44-45 and 54-55 at the left, as shown in Figure 3.

The photo-electric cell box 26 is identical with that shown at 2| except that it is inverted, the outer limits of the field of view of photocell 59 of box 26 being illustrated by lines 60-5I and 82-03 in the'section shown in Figure 2. As shown in Figure 3, the limits of view of all of the photocells are identical for the direction shown in Figure 3, since the cells are mounted one over the other. 1

The photo-electric cell boxes 22, 23, 24, 25 and 25, are constructed similarly to box 2|, except that the bailiing is so arranged as to allow cones of view defined as follows: For the photo-electric cell 64 of box 22, the outer limitations of the cone of view are defined by lines 55-65 and 81-88. The cone of view of photo-electric cell 89 of box 23 is defined by lines -1I and 12-13. The cone of view of photo-electric cell of box 24 is defined by lines 16-11 and 18-19. The cone of view of photo-electric cell 80 of box is defined by the line 8I-82 and 83-84.

It will be observed that the intermediate photoelectric cells 64, 69, 15 and 80 thus have cones of view extending throughout the total vertical area adjacent side wall I8, whereas photo-electric cells 48 and 59 of the bottom box 2| and top box 25, respectively, have cones of view which do not reach throughout the entire side wall area I8. As will later be explained, all the photo-electric cells act in parallel and the cumulative effect of the arrangement shown is that a light source of given luminosity moving along any area bounded by walls I6, I1, I8 and I9, produces approximately the same net electrical response except in the small upper area between top wall I6 and the line 60-5I and the small lower area between bottom wall I1 and the line 52-53, these areas being considered as outside the practical range of movement of the illuminated source. Thus, a projectile moving throughout the range along any path normal to the plane of Figure 2 and through the right-hand portion of Figure 2 will serve to activate all or nearly all of the photo-electric cells,

"whereas a projectile within the upper and lower Due to the finite width andspouse is approximately as much as when the gree of activation is greater and hence the re- 4 projectile is to the far right, as shown in Figure 2, and hence within the cone of view of a greater number of cells.

Fig-ure 4 illustrates the front view of a representative one of the photo-electric cell housings, for example that shown at 25. The horizontal baffling plates 85 and 85 and vertical side baffling plates 81 and 88 cut oil stray light. Thus, the top horizontalbailiing plates 85 are arranged so as to lie along the line 90-3I, the horizontal lower baffling plates 88 are arranged so that their 1 edges lie along the line 92-93. The vertical baffiing plates 81 are arranged so that their edges lie along the line 44-45 (Figure 3) and the 0D- posite vertical plates 88 have vertical edges lying along the line 46-41 shown in Figure 3. The corresponding bafiiing plates of the remaining photo-electric cell boxes 2|, 22, 23 and 28 are arranged as shown in Figures 2 and 3. The entire interior of the photo-electric cell boxes, the baffies and the interior of the range are finished a dead black so as to absorb any stray light.

At each photo-electric cell station (of which there are two illustrated in Figure 1) there is an amplifier apparatus generally designated I00. These amplifiers are preferably identical and hence only one need be described. The amplifier shown in Figure l is provided with two power supply lines L1 and L2 and a signal line S1 and a reset line R1 for the amplifier at station I. The signal line is designated S2 and a reset line is designated R2 for the amplifier at station 2. The signal lines S1 or S: and the reset lines R1 or R: are connected to the recorder generally designated IOI, illustrated in Figure 1. The amplifier power supply lines L1 and L2 of each emplifier are connected in parallel and are wired throughout the recorder so as to allow controlof the entire system from the recorder as hereinafter explained.

In Figure 5 there is illustrated an exemplary diagram of an amplifier suitable for use at stations I or 2 or any other additional stations that may be used in the system. The alternating current feeders L1 and L2 of the amplifier are connected through a suitable fuse I03 to the primary I04 of a transformer generally designated I05. The transformer is provided with a secondary I06 of suitable voltage for supplying energy to the filament I01 of a full-wave rectifier tube generally designated H0, and another secondary I08 is connected across the plates I09 and III of the rectifier tube. The mid-point II2 of the transformer secondary I08 is connected by line II3 to line N4, the latter being grounded at |I5. Plates I09 and III, being thus alternately negative, feed the grounded negative line II4 of the system. The filament I01 of the rectifier tube is connected through lines 5 or 1 to line H8 and thence through choke coil III! to feeder I20, which constitutes the positive output of the rectifier circuit. Line H8 is connected through condenser |2| to ground line IN, and line I20 is likewise connected through condenser I23 to a ground line. The two condensers |2| and I23 and the choke coil II9 thus serve as a filter network for smoothin out the pulsating current output of the rectifier. The transformer I05, rectifier I I0 and filter network 9- |2|-I23 thus constitute a direct current supply for the amplifier tubes of the system, and in Figure 5 these parts of the apparatus have been bracketed and so designated.

The system also includes a voltage regulator for the amplifier direct current supply, the regulater over the bracket bearing that notation. To accomplish such regulation, the positive feeder I is connected directly to the plate I26 former generally designated I3I. which is suitably energized by a primary winding I33. 'The mid-point I32 of the transformer secondary I is connected -to line I35 which constitutes the regulated positive voltage feeder of the therm ionic tube hereinafter described.

The regulator portion of the apparatus also includes the following components and circuits: From junction I36 on line II4 there extends a potentiometer circuit consisting of line I31, resistor I38, line I39, resistor I40 having an adjustable tap I4I, thence through line I42, resistor I43, line I44 having junction I45 thereon, and thence through resistor I46 to junction I41 on line I35. In parallel with the aforesaid potentiometer resistor, there is connected a circuit extending from junction I48 on linev I I4 through line I49 which is connected to the cold cathode I50 of a gasfilled regulator tube generally designated I5I, and thence through line I52, junction I53, line I54, junction I55, line I56, resistor I51 and line I58 to junction I59 on line I35. The regulator apparatus also includes a thermionic tube generally designated I60 having a cathode emitter I6I indirectly heated by filament I62 which is connected to any suitable filament voltage source. A first grid I63 is connected through line I64 to the adjustable tap I4-I on resistor I40. A second grid I65 is connected through line I66 to junction I45 between resistors I43 and I46. A screen grid I61 is connected through line I68 to junction I between lines I54 and I56. The plate I10 of the tube I is connected through line I1I, through junction I12 and thence through resistor I13 to junction I14 on the regulated positive voltage feeder I35.

The operation of the voltage regulator portion of the system is as follows:

In the event an increase of voltage occurs on alternating current feeders L1 and L2, this is reflected as an increase of voltage either permanent or transient in the direct current tube of full-wave rectifier tube IIO. Since the direct current output of the rectifier tube H0 is communicated to the positive voltage feeder I35 through the thermionic tube I25, it follows that the direct current, potential applied to line I35 is dependent upon the degree of conductivity of the tube I25 which is in turn under control of its grid I24. The voltage upon grid I24 is de termined by the relative values of resistor I13, the resistance from plate I10 to the cathode I6I of the tube I60. Whenever an increase of voltage occurs on line I20, it is desired to suppress this voltage in part. before being applied to line I35, and in order to accomplish this function, the resistance of tube I25 is accordingly increased by making the grid I24 more negative than during conditions of normal voltage. This more negative condition of grid I24 is accomplished by reducing the resistance of tube I60. The reduction of resistance is accomplished by the fact that an increase of voltage at I35 causes practically no increase of voltage at junction I53 due to the characteristics of tube I5I (variable resistance characteristic). However, an increase of voltage at I35 does cause an increase of voltage at junction I4I. Thus, the grid I63 is charged in a positive direction with respect to s cathode I6I causing a reduction in the resistance of tube I60; and as a result the grid I24of tube I25 becomes relatively more negative than during -normal operation, thus compensatin the in- For the optimum crease of voltage of the source. operation of tube I60, it is desirable to connect the screen grid I to tap I45, and thereby maintain a somewhat positive voltage on grid I65. The suppresser grid I61 is maintained at the same potential as the cathode emitter I6I via connection I54.

Wherever there is available an alternating supply source, substantially free from voltage fluctuation, the voltage regulator may be omitted and the output of rectifier I I0 connected directly across feeders I I4-I35. However, in usual commercial installations the connection of even relatively small loads causes transient voltage fluctuations, and as these are sufllcient to cause false indications, we have found it necessary to use the voltage regulator apparatus in order to have proper, fault-free functioning of this very sensitive apparatus.

There are six photo-electric cells, viz. 48, 59, 64, 69, 15 and 80 illustrated in Figure 2, but for simplicity only two of the photo-electric cells are shown in Figure 5, these being cell numbers 48 and 15. It will be understood that the remaining photo-electric cells are connected in parallel. As illustrated in Figure 5, the cathodes 48-0 and 15-C of the photoelectric cells are connected to the grounded negative line II4, whereas the anodes 48-A and 15-A are connected in parallel to photo-electric cell output line I15, which is in turn connected through a resistor I16 to a variable tap I11 on resistor I18. Resistor I18 is connected to ground line H4 at junction I19, and the opposite end of the resistor is connected through line I8I to junction 235 on line 234 and thence through line 234 to variable tap I99 on resistor I96. The thermionic tube I80 constitutes the second stage amplifier of the amplification and includes a cathode emitter I83 which is indirectly heated by filament I84, the filament being connected to any suitable source. The plate [86 of the tube I is connected through line I81, resistor I88 (having a variable tap I69), thence through resistor I90 and milliammeter I92 to the regulated positive feeder I35. From conjunction I95 on grounded negative feeder II4 there extends a potentiometer resistor generally designated I96 having variable taps I98, I99 and 200 thereon, the opposite end of resistor I96 being connected to junction 20I on the regulated positive feeder I35. Due to the voltage applied across the potentiometer resistor I96, there is accordingly established steady voltages at taps I98, I99 and 200. Tap I98 is connected through line 202 to the cathode emitter I83 of tube I80, and tap 200 is connected through line 203 to screen grid I85 of thermionic tube I00.

The first stage amplifier tube generally designated 206 includes a cathode emitter 201 which is indirectly heated by a suitable energized filament 208. The control grid 209 of the tube is connected through line 2I0, through junction 2| I and capacitor 2I2 to junction 2I3 on the photoelectric cell anode circuit I15. The cathode emitter 201 is connected by line 2I5 to junction 2I6, and thence through resistor 2I1 having a variable tap 2I8 and through line 2I9 and resistor 220 to tap 22I on the grounded negative feeder H4. The suppresser grid 223 of tube 206 is connected by line 224 to junction 225 and thence through line 226 to junction 2I6 on the cathode 7 circuit. Line 226 is connected directly to the control grid I82 of the second stage amplifier tube I68. Screen grid 226 of the tube 286 is connected through line 229 to junction 238, to which the plate 232 of the tube 286 is also connected by line 238. From junction 288 on the plate circuit there extends a line 234 which is connected at junction 235 to line I8I extending through resistor I16 to the negative feeder I I4.

The output of the second stage amplifier is at junction I69 on resistor I88 from which extends a circuit leading through line 239 and resistor 236 and thence through line 231 to a control grid 238 of a gas-filled trigger tube generally designated 248. The trigger tube 248 includes a filament 24I which is suitably fed by alternating current through the filament feed wires 242 and 243. A resistor 244 is connected across the filament feed wires, and the mid-point 245 of the resistor is connected through line 246, having junction 241 thereon, to junction 248, and thence through line 249, junction 258, variable tap 25I and resistor 252 to ground line 259.

The output of trigger tube 248 is by way of a circuit extending from plate 253, line 254, Junetion 255, line 268, thence through normally closed contacts 26I and 262 of a reset relay 265, through line 263, through the winding of a signal relay 261, which is the operated instrumentality, then through line 268, normally closed, manually operated switch 269, line 218, through variable re-' sistor 21I-212 to the positive terminal of a separate rectifier and filter network 28828I282. The output circuit continues from the negative output terminal 216 of the rectifier through line 211 to junction 258, thence through line 249, junction 248, line 246, resistor 244 to filament 2 of the tube 248. The plate of the trigger tube is connected to the filament by a circuit extending from junction 255 on the plate circuit, line 256, resistor 251, capacitor 258, through junction 248, line 246, resistor 244 to the filament 24 I.

The grid 238 of the trigger tube has a potential established by the output of tube I88. The potential applied to the grid 238 of the trigger tube may have a definite value in reference to ground. The output circuit of the trigger tube is connected at junction 255 to variable tap 25I on resistor 252, it being noted that one end of resistor 252 is grounded to line 259 and that the other end of the resistor 252 is connected to the voltage regulated positive feeder I of the amplifier system. Thus, the output of second stage amplifier tube I88 establishes a potential gradientfrom plate I86, through resistor I88, resistor I98, thence to the voltage regulated positive feeder I35, and then the latter is connected through resistor 252 to the grounded negative of the system. Accordingly, as the voltage'of tap I68 varies, grid 238 of the trigger tube has a definite voltage of reference with respect to the filament 24I of the trigger tube.

Operation of station amplifier 8 mediate voltagetap I88 on the potentiometer resistor I88 a circuit is established through line 224 to plate 282 and thence to cathode 281 (of tube 286), and through resistor 2I1, line 2I6 and resistor 228 to tap 22I on the grounded negative feeder H4. The current flowing in this circuit establishes an intermediate positive potential at tap 2I8 on resistor 2I1, and this is communicated through a resistor 2I4 to junction 2I I on the grid connection 2I8 of tube 286, thereby establishing a positive potential on the control grid 289 of the tube.

An intermediate positive potential is also communicated from cathode 281 of the first stage amplifier to the grid I82 of the second stage amplifier I88 and the latter tube is conductive. This condition of both tubes being conductive con.- tinues so long as the photocells are maintained at a given degree of darkness.

When light falls upon the photo-electric cells they become somewhat conductive, and accordingly serve to drain of! the electrical charge normally accumulated on line 2I8, the drain being through the circuit extending from Junction 2I I, capacitor 2 I 2 to junction 2 I8, and thence through the photo-electric cell (or cells) to the grounded negative supply line H4. The consequent decrease in positive voltage of grip 289 of tube 288 renders tube 288 less conductive and as a result, less current fiows through the plate circuit of the tube. As previously explained, the plate circuit of tube 286 traverses resistor 2I1, and the normal plate current fiowing when the photocells are dark establish the grid potential of the amplifier. Hence, when the photocells are illuminated the first effect is to reduce the plate current through tube 286, and as this occurs, tap 2I8 of resistor 2I1 (which is in the plate circuit) tends to shift to the negative. As a result, there is less tendency for the positive potential of grid 289 to be re-established and the decrease in conductivity of the tube 288 is hence cumulatively efiective in further decreasing the conductivity of the tube once the initiating impulse is received from the photo-electric cells,

Since the grid I82 of the second stage amplifier tube I88 is connected directly to the cathode of tube 286, any decrease in conductivity through tube 286 isimmediately reflected on tube I88 which likewise becomes less conductive. The plate circuit of the tube I88 extends from tap "I on the positive feeder I85 through the milliammeter m, resistors m and m, line m, plate I86, through the tube I88 to cathode I88, through line 282 to tap I88 on the resistor I96, and thence through the resistor to tap I85 on the grounded negative supply line H4. The decrease in conductivity of tube I88 (which is equivalent to an increase of resistance of the tube) causes the potential of tap I88 to become more positive, and

.this positive impulse is communicated directly through lines 285, resistor 286 and line 281 to the grid 288 of the trigger tube 248. The impulse causes the latter tube to trigger oil and begin to conduct.

The operation circuit of the trigger tube extends from the positive terminal 215 (of separate rectifier and filter 288--26I262), through resistor 212, terminal 2", line 218, normally closed manual reset switch 268, line 268, the coil grid of signal relay 261, line 288, normally-closed contacts 282-26I, of the reset relay 285, line 268, junction 255, line 254, to plate 258, thence through the trigger tube 248 to filament 28I,

through resistor 244 to the mid-point tap 248,

9 thence through line 246 to junction 248, line 249. junction 250, line 211 to negative terminal 216 of the rectifier 200-26I-282.

The circuit thus established through the trigger tube 240 causes the energization of relay 261 which closes its movable contact 260 upon its fixed contact 28I, thus establishing a circuit from the alternating current feeder L2, through the then closed contacts 280 and 28I to the signal line S1 which serves to actuate the recorder, as hereinafter explained. The trigger tube 240 continues to conduct once ionization is established in the tube, and therefore in order to interrupt the circuit, there are provided normally closed contacts 26I-262 of the reset relay generally designated 2'55. vFor opening these contacts a circuit is established at the recorder station, as hereinafter explained, from the alternating current feeder L2 at the recorder station, through Reset line R1 (or R2) to the coil of relay 265 and thence through line 284 to line I at the station amplifier.

Upon energization of reset relay coil 265, contacts 26I and 262 are separated, thus interrupting the output circuit of the trigger tube 240. This allows relay 261 to become deenergized. If desired, the circuit through the trigger tube may be interrupted by manually operating the normally closed switch 269.

In order to calibrate the amplifier apparatus, a voltmeter 288 is provided between lines 211 and the ground line 259. A millivoltmeter 290 is connected across lines 246 and 235 and a milliammeter I92 is provided in the plate circuit of tube I60. By means of these instruments and the various adjustments provided, the apparatus may be adjusted for operation under any desired degree of light change on the photocells.

Recorder and indicator The overall sensitivity of the system can also be varied by changing the voltage applied to the photocells, by varying the adjustment of tap I11 on resistor I18. A potential of 80 volts at point I11 gives good results; a reduction in voltage decreases the sensitivity of the system.

Referring to Figures 6 and 7, there is illustrated therein the circuit diagram and certain of the construction details of the recorder and indicator apparatus shown at the left in Figure 1. The recorder apparatus is provided with alternating current supply connections L1 and L2, L1 being grounded, and L2 being provided with a fuse 290 and a manually operated control switch 29I. The lines L1 and L2 extend through the recorder and connections are made from the left ends of -L1 and L2 of Figure 6 to each of the photo-electric cell station amplifiers, as illustrated in Figure 1. Accordingly, fuse 290 and switch 29I serve to control the entire system.

In the indicator and recorder mechanism there is provided a transformer generally designated :92, having a primary winding 293 connected by means of lines 294 and 295 to the alternating current feeders L1 and L2. respectively. The transformer is provided with a secondary winding 295 which is connected to line 295 at junction 291, and hence through line 295 to alternating current feeder L2. The opposite terminal of winding 296 is connected to a secondary feeder 298 which serves to supply low voltage alternating current potential to the various portions of the apparatus. The transformer is also provided with secondary winding 300 which is connected through lines 30I and 302 to the alternating 10 I current terminals oi the full-wave rectifier generally designated 304. The positive direct current terminals of the rectifier 304 areconnected by line 305 to junction 306 on the grounded alterhating current feeder L1. The negative terminal of the rectifier 304 is connected to line 301 which serves as a direct current supply line to various portions of the apparatus.

The recorder apparatus includes a tape drive motor generally designated 3I0, one terminal of which is connected by means of line 3 to junction 3I2 on the alternating current feeder L2. The opposite terminal of the tape drive motor 3 I 0 is connected by means of line 3I3 to stationary contact 3I4 of a slow release relay generally designated 3I5. A mechanical connection 340 extends from the motor 3I0 to a tape drive roll 342 and may include any suitable gearing so that the tape drive roll 342 is rotated at a desired slow or fast rate when the tape drive motor 3I0 is operated. Referring to Figure '7, the tape drive roll 342 serves to pull tape 343 from the tape supply roll 344. Tension is maintained upon the tape by means of an idler roller 345 which is held in contact with the motor-driven tape drive roll 342 by means of its mounting on arm 346. The arm 346 is pivoted at 341 and a spring 348 is attached thereto so as to cause the arm 346 to be pulled against the motor-driven tape drive roll 342, and thus any desired tension is maintained. The arm 346 is provided with a chute 349 along which the marked tape record slides from the machine.

The apparatus shown in Figure 7 also includes an illustrationof the condensers generally designated 392 and several elements of the rectifier generally designated 304. Above the tape roll there are provided one or more recorder solenoids generally designated 310 having windings 31I, one such recorder solenoid corresponding to each photo-electric station. The core of the solenoid includes an iron portion 312 and a brass stylus end 313, the core being spring mounted by means of spring 314 which is attached to the screw adjustment knob 315. Whenever the solenoid 310 is energized, the point of the stylus is brought into contact with the tape, thereby making a mark on the tape.

The slow-release relay 3I5 is provided with a movable contact 3I6 which is connected through junction 3I1 and line 3I8 to junction 3I9 on the grounded alternating current and positive direct current feeder L1. From junction 3II there extends line 320 which is connected at junction 32I to the winding of relay 3I5 and also to one terminal of a condenser 323. The opposite terminals of winding of the relay 3I5 and condenser 323 are connected at junction 324 and thence through line 325 to contact 326 of the vibrator relay generally designated 330. The slow release relay 3I5 is capable of instantaneous pick-up, but will remain energized for a period of A to 1 second after energization ceases, depending upon adjustment.

The vibrator relay 330 is provided with two active spring-mounted contacts 326 and 321, and inactive spring-mounted contact 328. A vibrator contact 329 is weighted at its outer end as shown at 33I. In the condition of rest, the weighted, springy contact 329 is in engagement with the active contact 321, but during such condition of rest the contact 326 is separated slightly from contact 321. The contact 328 is not connected in the circuits shown, but serves as a mechanical counterpart of contact 321 so as not to de-tune means? the relay. Contact 321 is connected through line 333 to junction 334 from which connection is made through the winding of the vibrator relay 330 and through a condenser 336 in parallel, to junction 331 and thence through line 335 to junction 338. The springy, weighted contact 329 of the vibrator relay is connected directly to the negative output line 301 of the rectifier. From junction 338 connections are made in parallel to each of the recorder control relays corresponding to each recorder station in the system.

A recorder control relay is provided for each photocell amplifier station, and hence there are two recorder control relays in the herein illustrated system. Thus, there are provided a recorder control relay 350 (corresponding to station 1) and a similar recorder control relay 380 (corresponding to station 2).

Relay 350 is provided with contacts 351, 353 and 355 which cooperate respectively with movable contacts 352, 354 and 356, the movable contacts being out of engagement with their corresponding stationary contacts when the relay is de-energized. The winding 351 of the relay is connected to line 359 at contact 352 and to signal line S1 extending to the photo-electric cell ampli fier station number 1, the circuit through coil 351 thus being from L1 at the recorder (Figure 6), thence through line 359, to contact 352, thence through winding 351 to line S1 which continues to the amplifier station (Figure through contacts 280 and 281 (when closed in response to a signal) and to feeder L2 at the amplifier of station 1.

When coil 330 is energized, reed 329 is drawn toward the coil forcing contact 321 against contact 326. When the circuit through the coil is broken, reed 329 is released and continues to vibrate. Snubbing of the reed 329 is prevented by the positioning of the contacts as shown; for example, in the event the next impulse through the coil occurs when the position of reed 329 is out of contact with contact 323. no circuit is established through the coil, and reed 329 hence continues to vibrate.

The energization of coil 351 of the recorder control relay 350 causes the simultaneous closure of each of its movable contacts 352, 354 and 356 upon the stationary contacts 351, 353 and 355, respectively. The closure of contact 352 upon contact 351 establishes a circuit from the negative terminal of the full-wave rectifier 304 through line 301 to vibrating reed contact 329. which is then closed a ainst contact 321. and thence through line 333, through the coil of the vibrator relay 330, line 335, junction 338. line 339. contacts 351 and 352, line 359, junction 358. feeder L1, junction 306 and line 305 to the positive terminal of the full-wave rectifier. The vibrator relay is hence energized and reed 329 begins to vibrate. As will be explained, this circuit throu h contacts 351352 remains closed only a short time but reed 329 continues to vibrate for a period of time after the direct current circuit through the coil of relay 330 has been interrupted.

The vibration of reed 329 causes the energization of the slow release relay 315 through a circuit beginning at the positive terminal of the full-wave rectifier 304, through line 305, junction 306, feeder L1, junction 319, line 318, junction 311, line 320, junction 321, thence through the coil of slow release relay 315, junction 324, line 325, to contact 326, which is in engagement with contact 321 when the latter is deflected due 12 to the engagement of the vibrating reed contacts 329 thereon. The circuit thus extends through contact 326 and contact 321 to the vibrating reed 329 and thence through line 301 to the negative terminal of the full-wave rectifier 3114. Direct current impulses are accordingly sent through the coil of slow release relay 315 so long-as relay 330 vibrates, and the movable contact 316 of relay 315 accordingly engages stationary contact 314. The slow release relay contacts 314-316 remain closed for 4-1 second after energization of the coil of the relay ceases, and while closed a circuit is maintained from alternating current feeder L1 through line 318 to junction 311, thence through closed contacts 318 and 314, line 313, through the tape-drive motor 316 and line 311 to junction 312 of the alternating current feeder L2. The energization of the tapedrive motor causes the rotation of the tape-drive roll 342 and the recording tape 344 is, therefore, rolled through the machine, either slowly or quickly, according to the design of the machine.

The energization of the recorder control relay 350 also establishes a circuit through the station recorder 3101, corresponding to station No. 1, as follows: From the lower terminal of transformer secondary to junction 291, thence through line 295 to alternating current feeder L2 to line 360, thence through junction 361, line 362, then closed contacts 355 and 356, line 363. through the coil of station recorder solenoid 310-1 and through line 298 to the upper terminal of the transformer secondary 296. The station recorder solenoid 3101 causes its solenoid 312-1 to be drawn downwardly until the stylus point 313--1 is brought into engagement with the tape 344. This causes a dot impression to be formed on the tape, for the station recorder solenoid is immediately withdrawn due to the deenergization of recorder control relay 350, as will be explained.

The recorder control relay 350 remains energized until the trigger tube output circuit of its corresponding amplifier is broken, this being accomplished by energizing the reset relay 265 of the amplifier station through contacts 353-354 of relay 350 as follows: From alternating current feeder L2 through line 360, junction 364, line 365, then closed contacts 353 and 354 to reset line R1 which extends to the reset relay 265 of the photocell station amplifier for station No. 1 (Figure 5), thence through the relay 265 and through line 284 to alternating current feeder L1. The energization of relay 265 causes contact 261 to be broken from contact 262, thus breaking the trigger tube output circuit through the signal relay 261 whereupon contact 280 of relay 261 moves out of engagement with its cooperating contact 281, accordingly de-energizing the recorder control relay 350 (of Figure 6). The entire sequence involves, initially, the energization of the signal relay 261, the consequent energization of recorder control relay 350 (which sets the vibrator relay 330 into operation, and thus causes the slow release to pick up and the tape drive motor to start together with the operation of the station recorder 3101 of station No. 1) and the operation of the reset relay 265 which, as just explained, causes the de-energization of the signal relay 261 and the consequent opening of the circuit of the recorder control relay 350, all this occurring in such rapid succession that it is not audibly distinguishable. Therefore, a light impulse upon the photocell, if amplified, causes the operation of the relays in 13 I sequence, thus causing the marking of the tape and movement of the tape from the recorder apparatus. The tape motor continues to operate for %-1 second after the first impulse (and mark) is pressed upon the tape and thus moves the tape to a fresh position for the recording of successive impulses;

The operation. of recorder control relay 380 at station No. 2 is exactly analogous to the operation of the relay at station No. I. It will be noted that in this instance also the signal is received from the photocell station amplifier of station No. 2 by way of signal line S: which communicates the impulse to the coil of recorder control relay 380 for station No. 2. This causes the closure of movable contacts 382, 388 and 388 upon stationary contacts 38I, 383 and 385, respectively.

The closure of contact 382 upon contact 38I establishes a circuit to the vibrator control relay 330 in the same manner as that established by contacts 35I and 352 of relay 350, and the vibrator control relay in turn causes the operation of slow release relay M and the operation of tape drive motor 3I0. The closure of contact 384 upon contact 383 establishes a circuit to the reset relay 285 of the photocell station amplifier corresponding to station No. 2, and the latter in turn causes the de-energization of the trigger tube output circuit and consequent de-energization of the signal relay 281 of station No. 2, which in turn opens the circuit through the recorder control relay of station No. 2. The closure of contact 388 upon contact 385 establishes a circuit through the station recorder 310-2 corresponding to station No. 2 which operates the stylus 3132 for marking the tape, this being exactly analogous to the operation discussed above which occurred when the contacts 355 and 358 are closed by the energization of relay 350 and station No. I.

Thus, assuming that the illustrated system is utilized for the testing of projectiles, the movement of the projectile along path III2 of Figure 1 past station No. I will cause the photocells of station No. I to be activated, with consequent movement of stylus 313-I corresponding to the station No. I into contact with tape 3. The movement of the projectile past station No. 2 will cause the photocells of station No. 2 to be activated, with consequent movement of stylus 313-2 corresponding to the station No. 2 recorder, into contact with tape 3. The movement of the projectiles will thus cause two dots to be marked upon the tape 3;

Where the tape-drive motor is arranged to move the tape relatively slowly, the two dots caused by stylus 313I and 313-2 will be nearly opposite each other because the tape, under such conditions will not move an appreciable distance during the time interval required for the movement of projectile from station I to station 2. The apparatus thus records the fact that the projectiles are moved past stations I and 2 and that a given condition of illumination of the projectile exists during the time of such movement. By designing the apparatus for rapid tape movement, the dots are spaced apart and a measure of the projectile velocity is afforded.

Specific examples of photocell station amplifier constants For the purpose of further illustration, but without any intention of limiting the invention, reference ismade to the following constants of one form photocell station amplifier which is useful for recording the performance of tracer l4 bullets. It will be understood, of course, that other specific designs of the apparatus are equally within the purview of the invention and that this example must therefore be considered merely as illustrative:

Photo-electric cells:

First stage amplifier 208 6SJ7 Second stage amplifier I 6V6 Trigger tube 200 287A Cold cathode tube I5! VR150 Amplifier I80 6SJ7 Thermionic tube I25 6B46 Rectifiers H0 and 28I 1 5Z3 Resistor 228 megohms 2 Resistors I16 and 2H do 60 Resistor 2I1 do 1 Resistors I18, I38 and I46 ohms 10,000 Resistor I96, 100 watts do 25,000 Resistor I40 do 15,000 Resistor I43 do 20,000 Resistor I51 do- 75,000 Resistor I13 megohm Resistor I88 ohms 10,000 Resistor I90 do 12,500 Resistor 236 do 100,000 Resistor 251 do 500 Resistors 25I and 212 do 25,000 Condensers I2I, I23 (and the condensers of filter network 282) microfarads 8 Condenser 258 do Condenser 2I2 do .00025 A photocell amplifier apparatus having the foregoing constants, when properly adjusted, is sufficiently sensitive to cause actuation of the signal relay 261 and consequent operation of the recorder when a piece of chalk or a yellow lead pencil is thrown through the photocell frame (Figure 2), and is unfailingly responsive to even the slightest illumination of a tracer bullet. Widely varying line voltage fluctuations do not cause false actuation of the signal relay 281.

It is also desirable to provide in the apparatus a bulb connected across the terminals of the recorder control relay for each station as illustrated at 390 and 3!. In this way a visual indication of the operation of the apparatus is provided, in addition to the record made on the record tape.

Many obvious variations will occur to those skilled in the art. Thus, the apparatus may be utilized for recording the movement of packages past a given point, for the passage of very small objects through a restricted area, and for recording the performance of ammunition. These and other aspects of the invention are deemed to be within the purview of the invention illustrated, described and claimed as follows:

What we claim is:

1. An apparatus for recording the movement of an illuminated body comprising a plurality of photocell stations located at spaced intervals along the path of movement of said illuminating body, each station having a photocell, an amplifier and a signal relay connected to the photocell and responsive thereto, a plurality of recorder relays at a remote station connected, respectively, to said signal relays of the photocell stations, a record tape and record moving means, means connected to and responsive to each of the recorder relays and responsive to actuation of any of said recorder relays for causing the actuation of the record moving means when the first of said recorder relays is actuated and for continuing said actuation for a short time inassam 1.8. terval, and means responsive to each recorder relay when actuated for marking the record.

2. An apparatus for recording the movement of an illuminated body comprising a plurality of photocell stations located at intervals along the path or movement 01' such illuminated body each station having a photocell, an amplifier and a signal transmitting relay connected to the photocell and responsive thereto and capable of remaining energized until positively de-energized, a plurality of recorder relays at a remote station each being connected to one of the signal relays, a record tape and tape moving means, means connected to all 01' said recorder relays and responsive to and 01 said operation of the recorder relays for causing the actuation of the tape moving means and 'for continuing said movement for a short time interval, means connected to and responsive to energization of each recorder relay for marking the tape and means connected to and responsive to the operation 01 each recorder relay for de-energizing the signal transmitting relay to which it is responsive.

3. In an apparatus for recording the movement of an illuminated'body past a plurality of stations located along the path of movement of said illuminated body, a photocell and amplifier therefor at each such station for transmitting an impulse responsive to the movement of the body past the station, a plurality of signal relays,

one being connected to each amplifier so as to be energized thereby, a record and motor drive therefor, vibrator relay means connected to all 01 the signal relays and responsive to the first or them which is operated by a transmitted impulse iro n the photocell station amplifiers for initiating operation 01 the motor drive and maintaining said operation for a predetermined minimum period of time, a record connected to the motor drive so as to be driven thereby when the motor is operated and individual marking devices, one for each of the signal relays, said marking devices being located so as to mark the record when its signal relay is operated.

4. A device for recording the movement of an illuminated body comprising a plurality of photocell stations located along the path of movement of said body, a first relay means at each or said stations for transmitting a signal in response to the movement of the body past the station, said relay means being adapted to remain operated until open circuited, a plurality of individual electrically operated recorderelements, a record 5. An apparatus for recording a series of instantaneous impulses oi rapid sequence'comprising a plurality of impulse generatin means and a plurality of control relays connected. respectively, thereto and operable thereby, a plurality of recording means each being independently operable and eachconnected to one o! the control relays, a record tape mechanically positioned so as to be marked by each of the recording means a motor drive for said tape, a vibrator relay connected to all of the control relays so as to be energized and set into vibration when any of said control relays is energized, said vibrator relay being capable of providing a plurality of circuit closures after being once energized, a slow release relay connected to said vibrator relay so as to be energized thereby and connected to said motor drive, said vibrator relay being adapted to maintain said slow release relay energized while said vibrator relay is in vibration, said vibrator relay having a duration of operable vibration of at least a predetermined minimum interval tape and a motor drive therefor, said tape being I located so as to be marked by said recorder elements a plurality of second relay means one such relay means being connected to each of the first relay means and connected to one of the recorder elements, each of said second relay means being adapted upon receipt of a signal from its respective first relay means to operate the recording means and concurrently to open circuit its first relay means to which it is connected, and motor control means connected to all of said second relay means for initiating operation of said motor drive in response to the first of said record relay means which is energized, said motor control means including means for maintaining said motor in operation for a predetermined minimum period of time.

whereby an initial energization thereof when the first of said control relays is energized will energize said motor drive for a predetermined minimum period of time.

6. In an apparatus having a record and drive means therefor for recording electrical impulses of instantaneous duration comprising the combination oi! a signal circuit; a first relay energized when the signal circuit is energized, a vibrating reed relay energized by said first relay, a slowrelease relay connected in circuit with the contracts of said vibrating reed relay whereby the slow release relay is energized by a series of impulses when the vibratin reed relay is set in motion responsive to the energization of said first relay, said drive means being connected to and controlled by said slow release relay, and means responsive to the operation of the first relay for interrupting the signal circuit.

HARRY WILLIAM HOFFMAN. ESTHER HELEN HEIMER, Special Administratria: of the Estate of Grover H. Helmer, Deceased.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,196,335 Clokey Aug. 29. 1916 1,555,893 Thompson Oct. 6, 1925 1,985,563 Fitz Gerald Dec. 25, 1934 2,176,312 Rassow Oct. 17, 1939 2,252,525 Reid et a1. Aug.'12, 1941 2,265,512 Brown et al Dec. 9, 1941 2,275,368 Krouse Mar. 3, 1942 2,294,730 Eggers Sept. 1, 1942 2,333,210 Stern Nov. 2, 1943 2,362,473 Dunham Nov. 14, 1944 2,369,659 Carr Feb. 20, 1945 2,387,544 Usselman Oct. 23, 1945 2,418,137 Noell Apr. 1, 1947 2,430,910 Fowler Nov. 11, 1947 FOREIGN PATENTS Number Country Date 562,461 Great Britain July 3, 1944 

